MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary...
Affected packages
| Ecosystem | Package | Affected | Fixed |
|---|---|---|---|
| https://cpan.org/modules | MIME-tools |
≥ 5.518, < 5.521 |
5.521 |
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-116266 libmime-tools-perl
- Ubuntu UBUNTU-CVE-2026-116266 libmime-tools-perl
Original description The description as published by the source.
MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous.
The multipart_boundary() method decodes RFC 2047 encoded words anywhere in the boundary, but the ambiguity check only fires when the whole value is one encoded word. A boundary such as abc=?us-ascii?Q?def?= is used as abcdef, and ambiguous_content() returns false.
Encoded words are not allowed in parameters, so other mail readers split the message on the literal value. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
Source: CVE.org (CVE Program・cvelistV5) NVD GitHub Advisory
References
- web metacpan.org
- web nvd.nist.gov
- web github.com